A directory service is a software application enabling the access to and management of a set of information entities, also called objects or entries, and associated attributes. The set of objects or entries is called a directory. The objects or entries in the directory may refer to persons, organization units, computer resources, documents or anything else. The attributes may be phone numbers, organization units' name, computers' or documents' characteristics, etc. Functions are usually provided to search, browse and update the directory.
The Lightweight Directory Access Protocol (LDAP) is an example of protocol for accessing directory trees through TCP/IP. LDAP is widely supported. A client starts a LDAP session by connecting to a LDAP server, and the client can send an operation request to the LDAP server, for instance to search for a directory entry or to add, delete or modify an entry.
An object or entry in the directory has one or more attributes. Each attribute has one name (or key) and one or more values associated with the name (or key). A particular type of entry is an alias entry, i.e. an entry including an attribute pointing to another entry. In the exemplary context of X.500 and LDAP, Howes T. A., An X.500 and LDAP Database: Design and Implementation, University of Michigan, Dec. 2003, discloses alias entries in a directory (see page 1, bottom of right-hand column: “Alias entries are allowed, which point to other entries, circumventing the hierarchy” and page 2, FIG. 1).
It is desirable to provide methods, controllers, servers, systems and computer programs to improve the handling of adding and deleting operations in relation to entries in such directories, notably by aiming at more reliability without increasing the signalling and architecture complexity.